In known closures, e.g. for cans, the sealing pressure is produced on the seal by means of the resilient character of the closure member only. Known closures for jars and bottles do include some means in the form of a screw or a plunger to increase or decrease the closing pressure of the closure member against the internal walls of the bottle or jar. However, such closures have not been found to be suitable for satisfactorily sealing the openings of cans, in particular soda or beer cans. Moreover, the removal of the known closure members for soda or beer cans is quite difficult because of the high pressure that is required by the resilient member against the walls of the opening of the soda can or beer can.